40 Important Electromagnetic induction MCQ Question and Answer | PDF Free Download
1.The core of the coil has a length of 200 mm. the inductance coil of 6 mH. If the core length is doubled, all other quantities, remaining the same, the inductance will be
- A3 mH
- B12 mH
- C24 mH
- D48 mH
2.The self-inductance of two coils are 8 mH. If the co-efficient of coupling is 0.5, the mutual inductance of the coil is
- A4 mH
- B5 mH
- C6 mH
- D12 mH
3.Two coil have inductance of 8 mH and 18mH and co-efficient of coupling of 0.5. if the two coils are connected in series aiding, the total inductance will be
- A32 mH
- B38 mH
- C40 mH
- D48 mH
4.A 200 turn coil has an inductance of 12 mH. If the number of turns is increased to 400 turns, all other quantities ( area, length etc.) remaining the same, the inductance will be
- A6 mH
- B14 mH
- C24 mH
- D48 mH
5.Two coils have self-inductance of 10 h and 2 h, the mutual inductance being zero. If the two coils are connected in series, the total inductance will be
- A6 H
- B8 H
- C12 H
- D24 H
6.In case all the flux from the current in coil 1 links with coil 2, the co-efficient of coupling will be
- A2.0
- B1.0
- C0.5
- DZero
7.A coil with negligible resistance has 50 V across it with 10 mA. The inductive reactance is
- A50 ohms
- B500 ohms
- C1000 ohms
- D5000 ohms
8.Lenz?s law is a consequence of the law of conversion of
- AInduced current
- BCharge
- CEnergy
- DInduced e.m.f
9.The co-efficient of coupling between the air core coils depends on
- ASelf-inductance of two coils only
- BMutual inductance of two coils only
- CMutual inductance and self-inductance of two coils
- DNone of the above
10.An average voltage of 10 v is induced in a250 turns solenoid as a result of a change in flux which occurs in 0.5 seconds. The total flux change is
- A20 Wb
- B2 Wb
- C0.2 Wb
- D0.02 Wb
11.Which of the following inductor will have the least eddy current losses?
- AAir core
- BLaminate iron core
- CIron core
- DPowdered iron core
12.Two 300 ?H coils in series without mutual coupling have a total inductance of
- A300 ?H
- B600 ?H
- C150 ?H
- D75 ?H
13.A coil induced 350 mV when the current changes at the rate of 1 A/s. the value of inductance is
- A 3500 mH
- B350 mH
- C250 mH
- D150 mH
14.Current charging from 8 A to 12 a in on second induced 20 volts in a coil. The value of inductance is
- A5 mH
- B10 mH
- C5 H
- D10 H
15.Which circuit elements will oppose the change in circuit current?
- AResistance only
- BInductance only
- CCapacitance only
- DInductance and capacitance
16.A crack in the magnetic path of an inductor will result in
- AUnchanged inductance
- BIncreased inductance
- CZero inductance
- DReduced inductance
17.A coil is wound on iron core which carries current I. the self-induced voltage in the coil is not affected by
- AVariation in coil current
- BVariation in voltage to the coil
- CChange of number of turns of coils
- DThe resistance of magnetic path